The following results were reported: (1) neoplastic transformation of the SV40 T-antigen-immortalized human epidermal keratinocyte (RHEK-1) line by the v-fos oncogene, (2) demonstration of neoplastic transformation of RHEK-1 line by exposure to 2,3,7,8-tetrachlorodibenzo- p-dioxin, (3) demonstration of RHEK-1 line as a suitable model to examine the actions of parathyroid hormone-like peptide (PLP), (4) immortalization of human renal proximal tubule cells by adenovirus 12- SV40 (Ad 12-SV40) virus, and (5) demonstration of neoplastic transformation of a human prostate epithelial cell line by the v-Ki-ras oncogene.